Piatigorsky J
Laboratory of Molecular and Development Biology, National Eye Intitute, National Institutes of Health, Bethesda, Maryland 20892-2730, USA.
Ann N Y Acad Sci. 1998 Apr 15;842:7-15. doi: 10.1111/j.1749-6632.1998.tb09626.x.
The abundant water-soluble proteins, called crystallins, of the transparent, refractive eye lens have been recruited from metabolic enzymes and stress-protective proteins by a process called "gene sharing." Many crystallins are also present at lower concentration in nonocular tissues where they have nonrefractive roles. The complex expression pattern of the mouse alpha B-crystallin/small heat shock protein gene is developmentally controlled at the transcriptional level by a combinatorial use of shared and lens-specific regulatory elements. A number of crystallin genes, including that for alpha B-crystallin, are activated by Pax-6, a conserved transcription factor for eye evolution. Aldehyde dehydrogenase class 3 and transketolase are metabolic enzymes comprising extremely high proportions of the water-soluble proteins of the cornea and may have structural as well as enzymatic roles, reminiscent of lens enzyme-crystallins. Inductive processes appear to be important for the corneal-preferred expression of these enzymes. The use of the same protein for entirely different functions by a gene-sharing mechanism may be a general strategy based on evolutionary tinkering at the level of gene regulation.
透明且具有屈光性的眼球晶状体中富含一种名为晶状体蛋白的水溶性蛋白质，它们是通过一种叫做“基因共享”的过程从代谢酶和应激保护蛋白演变而来的。许多晶状体蛋白在非眼部组织中也有较低浓度的存在，在这些组织中它们发挥着非屈光性的作用。小鼠αB-晶状体蛋白/小热休克蛋白基因复杂的表达模式在转录水平上受到共享调控元件和晶状体特异性调控元件组合使用的发育控制。包括αB-晶状体蛋白基因在内的许多晶状体蛋白基因都由Pax-6激活，Pax-6是一种在眼睛进化过程中保守的转录因子。3类醛脱氢酶和转酮醇酶是代谢酶，在角膜的水溶性蛋白质中占比极高，可能同时具有结构和酶促作用，这与晶状体酶-晶状体蛋白类似。诱导过程似乎对这些酶在角膜中的优先表达很重要。通过基因共享机制将同一种蛋白质用于完全不同的功能，可能是一种基于基因调控层面进化修补的通用策略。
